A macromonomer crosslinker was synthesized by reacting an hydroxy-terminated ethylene-butylene diol copolymer with an excess of acrylic acid in toluene. H-1-, C-13-, and attached proton test (APT) NMR. Fourier transform IR, and gel permeation chromatography were used to characterize the macromonomer crosslinker. Its dilute solution behavior was also compared with the base diol, The addition of the ester moiety to the copolymer backbone did not involve any other side reactions, as evidenced by the similarities in the structures of the macromonomer crosslinker and the diol.